NLA Editor: select specific NLA track in python
Set the NLATrack.select property to true.

Sample script, selects all tracks, on context object, which have a name beginning with "Nla" The zeroth position track is set to active. 

import bpy
from bpy import context 

ob = context.object
ad = ob.animation_data
if ad:
    for i, track in enumerate(ad.nla_tracks):
        # select all whose name starts with "Nla"
        track.select = track.name.startswith("Nla")
        # make active track if in pos 0
        if track.select and not i:
            ad.nla_tracks.active = track